NHANES

The History of NHANES

The NHANES program began in the early 1960s and has been conducted as a series of surveys focusing on different population groups or health topics. In 1999, the survey became a continuous program that has a changing focus on a variety of health and nutrition measurements to meet emerging needs.

The Health Problem Under Study

The National Health and Nutrition Examination Survey (NHANES) is a program of studies designed to assess the health and nutritional status of adults and children in the United States. Anemia Body composition and bone density Cardiovascular diseases Diabetes Environmental exposures Infectious diseases Kidney diseases Nutrition Obesity Oral health Physical activity and physical functioning Reproductive history and sexual behavior Respiratory diseases (asthma, chronic bronchitis, emphysema) Sexually transmitted diseases

Advantages, Disadvantages, and Sources of Errors

The exam ensures that all data is accurate, however there is trust placed on the individual to answer honestly to questions regarding sensitive topics. The survey examines a nationally representative sample of about 5,000 people each year, for a population of 327 million. 2 to 5 year delays in data availability Weighting software needed to obtain national estimates from survey data

The Study Design

Cross-sectional study The survey is unique in that it combines interviews and physical examinations All counties are formed into 15 groups based on similar characteristics One county is selected from each group, and from there smaller groups are selected (usually 20 to 24) Household groups are then identified from the groups, typically 30 within each group NHANES interviewers visit and interview each member of the household

Hypothesis

Findings from these studies will help determine the prevalence of major diseases and risk factors for diseases. NHANES findings are also the basis for national standards for such measurements as height, weight, and blood pressure.

Where the Study Took Place

Health interviews are conducted in respondents' homes. Health measurements are performed in specially designed and equipped mobile centers, which travel to locations throughout the country. The study team consists of a physician, a dentist, medical and health technicians, and dietary and health interviewers. Many of the study staff are bilingual (English/Spanish)

How has this study informed or influenced the study or field of public health?

Facts about the distribution of health problems and risk factors in the population give researchers important clues to the causes of disease. Information collected from the current survey is compared with information collected in previous surveys. This allows health planners to detect the extent various health problems and risk factors have changed in the U.S. population over time. By identifying the health care needs of the population, government agencies and private sector organizations can establish policies and plan research, education, and health promotion programs that help improve present health status and will prevent future health problems.

What are the conclusions drawn from this study?

Information collected in this survey will help the Food and Drug Administration decide if there is a need to change vitamin and mineral fortification regulations for the Nation's food supply. National programs to reduce hypertension and cholesterol levels continue to depend on NHANES data to steer education and prevention programs toward those at risk and to measure success in curtailing risk factors associated with heart disease, the Nation's number one cause of death. New measures of lung function will further our understanding of respiratory disease and better describe the burden of asthma in the United States.

What are the conclusions drawn from this study?

Overweight prevalence figures have led to the proliferation of programs emphasizing diet and exercise, stimulated additional research, and provided a means to track trends in obesity. Data have continued to indicate that undiagnosed diabetes is a significant problem in the United States. Efforts by government and private agencies to increase public awareness, especially among minority populations, have been intensified. These are just a few examples of what survey findings have meant. The current program promises continuing contributions and some new initiatives.

What are the conclusions drawn from this study?

Past surveys have provided data to create the growth charts used nationally by pediatricians to evaluate children's growth. The charts have been adapted and adopted worldwide as a reference standard - and have recently been updated using the latest NHANES figures. Blood lead data were instrumental in developing policy to eliminate lead from gasoline and in food and soft drink cans. Recent survey data indicate the policy has been even more effective than originally envisioned, with a decline in elevated blood lead levels of more than 70% since the 1970s.

Data Collected

the aspects of a person's lifestyle, constitution, heredity, or environment that may increase the chances of developing a certain disease or condition—will be examined. Smoking, alcohol consumption, sexual practices, drug use, physical fitness and activity, weight, and dietary intake will be studied. All participants visit the physician. Dietary interviews and body measurements are included for everyone. All but the very young have a blood sample taken and will see the dentist. Depending upon the age of the participant, the rest of the examination includes tests and procedures to assess the various aspects of health listed above. In general, the older the individual, the more extensive the examination.